A questionable foray into breast cancer care nearly two decades ago — when mandated insurance coverage of bone-marrow transplants turned out to be more harmful than helpful — should have yielded caution at the State Capitol when lawmakers weighed a dubious new screening mandate this year.

Instead, lawmakers thoughtlessly disregarded the troubling precedent as they rushed to pass what’s often referred to as the “Are You Dense?” bill. The legislation was pushed by a small but vocal national advocacy group but, tellingly, not leading medical organizations. Even with the catchy moniker, the legislation failed to generate adequate debate.

The legislation requires providers to notify women who are determined through mammography to have dense breast tissue, which may increase breast cancer risk or make it more difficult to spot cancer early on in mammograms. About 40 percent of American women are estimated to have dense tissue, meaning their breasts have more fibrous or glandular tissue. As a result of the legislation, thousands of Minnesota women who get a mammogram this year and in coming years will get this notification.

The most expedient course of action for state lawmakers was to vote yes on this bill, especially during a short and crowded session. More than a dozen other states had similar laws on the books. “Knowledge is power” is an easy concept to grasp and tout to constituents, especially when lobbyists crusading under breast-cancer-awareness pink ribbons are asking for it.

But good politics don’t always make for good policy. The “Are You Dense?” legislation, pushed by a Connecticut-based advocacy group, is a reminder of that. Had lawmakers consulted medical experts before they voted to meddle in women’s medical care, they would have discovered that the issue is far more complex than it first appears.

Questions about disease screening — who should be tested and when — are among the thorniest in all of medicine. Yes, it’s good to detect disease early. But doing so also needs to yield more than knowledge. It needs to lead to measurable gains in outcomes — for example, reducing the death rate from the disease.

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According to the American Cancer Society, breast cancer is the second leading cause of cancer death in women. About 233,670 new cases of invasive breast cancer will be diagnosed this year. There will be an additional 63,570 cases of noninvasive breast cancer diagnosed. To read the society’s overview of breast cancer risk factors, go to http://tinyurl.com/9ycvh3c

Value calculations also need to take into account the costs of these procedures. That includes the dollars spent on the test and any further screening it might lead to — an important consideration in the era of high-deductible health plans and soaring medical costs. Then there’s emotional cost of the false positives such procedures invariably lead to.

Among the reasons that respected organizations such as the American Cancer Society and the Minnesota Medical Association stayed neutral on the bill instead of supporting it — something else that should have been a red flag to lawmakers — is that there’s little medical consensus on what other tests women with dense breast tissue should undergo.

Ultrasounds and MRIs can detect cancers that mammograms do not show. But they also pick up findings that are not cancer, leading to biopsies or other procedures that aren’t needed. Whether or not these additional screenings for women with dense breast tissue improve outcomes is unclear. More research is needed to establish that they do.

It’s also worth noting that women may have to pick up the costs of additional breast screenings. Insurers may not cover it, and the legislation doesn’t require them to do so.

The “Are You Dense?” website states that the risk of cancer among those with dense breast tissue has been a “best-kept secret.” The reality is that information about breast density and other cancer risk factors (it’s hardly the only one) is easy to find.

Women and their doctors should be talking about breast density in the aftermath of a mammogram, but it needs to be pointed out that many of them already were. More awareness is always good, but there are better ways to do it than by passing legislation. The state doesn’t need to try to force conversations between patients and caregivers by dictating what doctors have to tell patients and requiring notification that is “going to scare the hell out of a lot of Minnesota women,’’ according to one Twin Cities physician. (And then leave them in a situation where there’s no consensus on what to do next.)

The notification may also send the wrong message that this is the only breast cancer risk factor that women need to worry about. That’s dangerous and not true.

State lawmakers were wise enough in 2004 to repeal the bone-marrow coverage mandate. Lawmakers in 2015 need to revisit the “Are You Dense?” law and make sure that their actions were in the best interests of patients, not an advocacy group.